EVERY WEEK, somewhere between 23 million and 29 million Americans tune in to National Public Radio. In the apples-and-oranges world of television and radio ratings, it’s hard to know precisely how to compare TV’s daily numbers with radio’s weekly audiences. But there seems to be little question that NPR is now the second-largest broadcast news source in the United States, still trailing the network newscasts, but catching up rapidly — and far ahead of the cable news shows upon which media critics regularly dump barrels of ink.

NPR’s audience has at least doubled in the past decade. The only radio program with a larger audience than NPR’s two drive-time newscasts — Morning Edition and All Things Considered — is Rush Limbaugh’s talk show. The NPR audience tends more toward middle age than youth; in the past year or so, for instance, I’ve heard Lyle Lovett and, just last week, John Prine come on ATC to plug their latest CDs. But that’s still a lot younger than the network news audience. And whereas the television news audience is shrinking because it defies cultural trends, the public-radio audience is growing along with those trends.

In a media culture bogged down by charges of liberal (and, increasingly, conservative) bias, NPR largely succeeds in satisfying the broad middle — something even conservatives might realize if they’d listen. After all, Fortune 500 companies and other big underwriters would pull out if right-wing sneers about NPR’s being "Radio Managua" (to cite a chestnut from the 1980s) had any truth to them. You will hear liberal bias on many public stations, but that usually comes from the BBC World Service, whose content is used to fill many of the off-hours, not NPR. As for local programming, public stations in Boston, New York, Washington, and elsewhere may have hosts who are liberal, but they’re more successful at offering balance than are their right-leaning counterparts on commercial radio.

This is not a paean to NPR. Though much of the programming is pretty damn good, it’s gotten less edgy and far more mainstream in recent years as it has become the primary news source for many of its listeners. I’d like to hear more-probing interviews, less deference to power, and a political conversation that extends beyond commentators E.J. Dionne and David Brooks, a couple of centrists who try but don’t quite succeed at being ideological adversaries. And though I was not a huge fan of Morning Edition anchor Bob Edwards, he was a competent and serene presence, and I still don’t know why he got whacked. (Edwards now hosts a news and talk show on the XM satellite network.)

My point isn’t that NPR is better than the network newscasts. Rather, it is that NPR reaches people where they are — in their cars, at home packing up lunches or making dinner, or while they’re working. Television demands that you look and listen, and, in the case of the network broadcasts, that you do so during a narrow, inconveniently timed half-hour opening. Radio accommodates the multitasking society we have increasingly become. Consider: according to the US Department of Transportation, the number of workers commuting by private vehicle more than doubled, from 43 million to 97 million, between 1960 and 2000. Between 1980 and 2000, the proportion of workers commuting more than 45 minutes one way rose from 11 percent to 15 percent, and that of workers commuting less than 15 minutes dropped from 34 percent to 28 percent. What do they have to do when they’re stuck in traffic other than listen to the radio?

People are working harder, too. According to the American Sociological Association, the average number of hours that men (43.1) and women (37) work every week actually dropped slightly between 1970 and 2000. But the rise of two-earner and single-parent households means that there is less time and more pressure at home than was the case in the stereotypical 1950s and ’60s household, with a working father and a stay-at-home mother. Sociologists Kathleen Gerson, of New York University, and Jerry Jacobs, of the University of Pennsylvania, have written, "Even if the length of the work week had not changed at all, the rise of families that depend on either two incomes or one parent would suffice to explain why Americans feel so pressed for time." They note, for example, that the combined work week of two-earner households rose from 53 to 63 hours between 1970 and 2000. There’s just no time on the schedule for a half-hour with the network news. In such a time-pressed culture, radio not only makes more sense than television; it also has advantages over print, another medium that demands your undivided attention. Says independent journalist Bruce Gellerman, a radio veteran who’s worked for both NPR and Boston’s WBUR (90.9 FM): "It’s the one medium that is transportable, and, more importantly, you can experience it while you’re doing something else."

Weirdly enough, NPR’s funding base is more secure than that of networks news, too. Though nominally a government service, public radio, starting in the Reagan era, has become largely privatized, living off listener contributions and corporate-underwriting announcements that sound more and more like commercials. NPR is also flush with a $236 million endowment from Joan Kroc, the widow of McDonald’s magnate Ray Kroc. The public stations that subscribe to NPR — including Boston’s WBUR and WGBH (89.7 FM) — also receive most of their money from listeners and underwriters.

By contrast, the major networks are now all owned by corporate conglomerates: ABC is part of Disney, NBC is a subsidiary of General Electric, and CBS is an arm of Viacom. These conglomerates are invariably more interested in squeezing profit out of the bottom line than they are in reporting the news. And with cable and satellite channels increasingly taking audience share away from the networks, the very advertising model on which they depend is now threatened. The result, according to the American Journalism Review: whereas the major networks once staffed bureaus around the world, today NPR’s 14 foreign bureaus outnumber those of ABC, CBS, NBC, and Fox.

"If you are a thinking person looking for the most intelligent coverage of world and national news in America, you would have to put public radio at the top of the heap. It has taken over the reign in broadcasting that institutions like CBS used to have," says Robert Thompson, director of the Center for the Study of Popular Television at Syracuse University. "Broadcasting’s crowning achievement at this point, in terms of the news, is far and away public radio."

Adds David Mindich, who chairs the journalism department at Saint Michael’s College, in Colchester, Vermont, and is the author of Tuned Out: Why Americans Under 40 Don’t Follow the News: "You could certainly make the argument that among elites, people tend to listen to NPR in much greater numbers than television news." And he offers a devastating comparison between NPR and the evening network newscasts. "People consume media that will help them in their conversations," Mindich says. "People tend not to talk about the evening news, at least anecdotally. I’ve seen that. People don’t say, ‘Oh, did you see the report on CBS last night? Did you hear what Peter Jennings said last night on ABC?’ People tend to quote stories on NPR, at least among people I know who are seriously following politics and news."